The present invention is directed generally to electrical resistance heat generation devices and more particularly to an improved impulse heat generation and sealer apparatus for rapidly generating heat to form in some preferred embodiments a bond between sheets of a polymeric material and to rapidly dissipate the heat to prevent damage thereto.
In the prior art, various techniques have been utilized for bonding together two sheets of a polymeric sheet material such as may be done in closing the top of a plastic bag or in the formation of a container from two sheets of a polymeric material. One such device has been the impulse sealer.
Prior art impulse sealing devices have generally been constructed of an aluminum block which is water cooled and contains on the sealing surface thereof a flat wire which must be carefully formed and is generally fragile, difficult to make, expensive to construct, and lacks any substantial durability. Thermal expansion and contraction of such flat wire impulse sealers frequently results in undesirable creepage, inaccurate and inefficient sealing, and slow operation of cycles. In fact, such prior art flat wire impulse sealing devices have usually required as much as approximately two seconds to effect a seal as compared with approximately two hundred microseconds for conventional heat sealing.
In view of these and other difficulties associated with prior art impulse sealing devices, improvement is indicated and an object of the improved impulse generation and sealer apparatus of the present invention is to substantially reduce these difficulties.